1. Technical Field
This invention relates generally to electronic control systems for electrically heated cold weather garments, and more particularly to a hybrid electronic control system and method for controlling electric heating levels within an electrically heated, cold weather garment.
2. Discussion
Electrically heated garments, such as electric shirts, pants, socks, gloves and the like are helpful in combatting the effects of cold temperatures on a person subject to prolonged exposure to severe weather. Heated garments can prove helpful to persons such as sportsmen, farmers, construction workers, public officials, and military personnel, who frequently are exposed to cold weather for prolonged periods of time.
Problems with prior art electronic control systems for electrically heated garments have existed with respect to the ability to heat a plurality of discrete heating zones of the garment independently. Heating different zones individually with a high degree of control is desirable because of the varying rate at which different parts of the body lose heat. The extremities, i.e., hands, feet and head, for example, suffer from a greater heat loss than the torso. In addition, physical activities of the wearer of the garment can cause different parts of his body to generate heat at varying levels. A system which applies the same level of heat to all areas of the garment can therefore produce temperature levels within the garment that are uncomfortable to the wearer.
Prior art electronic control systems, to be able to control the heat applied to various zones of the garment independently, typically require an independent, user actuable switch for each zone to enable or interrupt the current flowing to its associated heating element or elements. In these systems the control of the wearer over the amount of heat generated by the various heating elements of the suit is quite limited; the heating elements are either fully on or fully off, thereby generating either maximum heat or no heat at all. In some prior art systems, attempts have been made to provide variable control over the heat generated by each heating element by using switches to selectively connect a power source to a plurality of heating elements having different heat generating capabilities or characteristics. In this manner some control is allowed over the amount of heat generated for a particular zone of a garment, but still only in fixed steps. Prior art systems of the types described above are disclosed in the following U.S. Pat. Nos.:
______________________________________ U.S. Pat. No. Issued Inventor(s) ______________________________________ 710,429 1902 Collins et al 3,858,028 1974 Kerr 4,404,460 1983 Kerr 4,251,718 1981 Cole ______________________________________
The need for multiple, user actuable on-off switches to control the temperature of various zones of a heated garment is inconvenient to the wearer of a heated garment as he or she carries on many outdoor activities. Furthermore, a temperature control system which allows only for fixed increment changes in the amount of heat generated by the various heating elements of the garment does not provide the degree of temperature control needed to produce a comfortable temperature environment within the garment under widely varying environmental conditions and wearer activities.
It would therefore be desirable to have an electronic control system capable of selectively increasing or decreasing the power level or heating applied to each zone of an electrically heated garment independently of the other zones.
It would also be advantageous if such a control system could also be operated, through a single user adjustable control, to increase or decrease the power levels being applied to all the zones simultaneously and uniformly. Such a feature would allow a wearer of the garment to quickly raise or lower the overall warmth provided by the suit as much or as little as needed to compensate for changing environmental conditions.
It is therefore a principal object of the present invention to provide an electronic temperature control system for controlling the power levels of heating applied to a plurality of predetermined zones of a cold weather garment independently of each other.
It is a further object of the present invention to provide a temperature control system and a method capable of allowing a wearer of the garment to adjust the heating level of a particular zone of the garment to achieve a desired temperature level, independently of the other zones of the garment.
It is another object of the present invention to provide a temperature control system capable of rapidly increasing or decreasing the temperature of each zone of the garment simultaneously and in a uniform manner.